The present invention relates to a disposition structure of a drive gear located at the output end of a zoom gear train in a camera.
In a camera having a zooming mechanism, a lens-barrel block is retractably disposed in a cylindrical lens-barrel portion formed on a housing, and a zoom gear train is disposed outside the lens-barrel portion. A drive gear constituting a zoom gear train and being located at the output end of the zoom gear train is engaged with a gear portion of the lens-barrel block so that the lens-barrel block moves forward and backward of the lens-barrel portion via a mechanism for converting a rotary motion into a linear motion. In a camera of this type, in many cases, each gear constituting a zoom gear train including a drive gear, has a shaft extending forward and backward of the lens barrel portion, in other words, extending forward and backward of the camera, and the rear end of such a shaft is supported by the wall portion provided at the rear of the lens-barrel, and the front end thereof is supported by a holding member provided independently of the lens barrel.
Since the drive gear is engaged with the gear portion of the lens-barrel block through a notch formed on the lens-barrel portion, the drive gear is inserted into the interior of the wall portion swelling outwardly in the direction of the radius of the lens-barrel portion from the front thereof in order to prevent a light from entering through the notch into the lens-barrel portion.
Therefore, in this disposition structure of a zoom gear train, there is a recognized disadvantage that assembly of the drive gear consumes much time and effort because the drive gear has to be engaged both with a gear of a zoom gear train and a gear portion of the lens barrel block from the front of the lens-barrel portion in a direction in which the axes of such gear and gear portion extend.
In addition, since all the gears constituting a zoom gear train are to be supported on their shaft by the holding means after they are assembled, there is also a recognized disadvantage that, in case where a test on a zoom gear train excluding a drive gear is to be conducted, a test on the zoom gear train cannot be conducted easily because it requires quite cumbersome procedures such as removing the holding member, taking out the drive gear, then after the drive gear has taken out, mounting the holding member again.
The present invention is thus contemplated with aforementioned circumstances in view. Accordingly, it is an object of the present invention to provide a disposition structure of a zoom drive gear wherein both assembly of the drive gear and testing on a zoom gear train excluding the drive gear may be performed easily.
In order to achieve the object described above, the present invention provide a camera comprising a lens-barrel block disposed in a cylindrical lens-barrel portion formed on a housing so as to be movable along the axis of the lens-barrel portion, a zoom gear train disposed outside of the lens-barrel portion, a drive gear constituting the zoom gear train and being located at the output end of the zoom gear train and engaged with the gear portion of the lens-barrel block, and the lens-barrel block being moved along the aforementioned axis of the lens-barrel portion by driving the zoom gear train, characterized in that the drive gear receiving portion for receiving the drive gear is provided between the lens-barrel portion and the shielding cover removably mounted to the lens-barrel portion from radially outside of the lens-barrel, that the drive gear receiving portion includes a notch formed on the lens-barrel portion through which the drive gear engages with the gear portion of the lens-barrel block, and that assembling of the drive gear is performed by moving the drive gear from radially outside of the lens-barrel portion inwardly toward the notch with the shielding cover opened.
According to the present invention, the assembly of the drive gear may be performed easily since the drive gear is engaged both with the gear of the zoom gear train and the gear portion of the lens-barrel by moving the drive gear inwardly along the direction orthogonal to the axes of the gear and the gear portion described above.
In addition, removing the shielding cover enables the drive gear to be removed alone, which facilitates the test on the zoom gear train.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-169215 (filed on Jun. 16, 1999), which is expressly incorporated herein by reference in its entirety.